sheet of cells that cover all free body surfaces (inside and out), forming an interface between two environments

What are the functions of epithelium tissue?

Protection: often in areas that get scraped off

Absorption: intake of molecules and substances

Filtration: closely fitted cells can form a "strainer" with small holes

Secretion: release of molecules and substances

Senory reception

Apical surface:

Macrovilli

Cilia

Macrovilli

increase in surface area and used for absortion

fingerlike extentions of epithelial cells lining some parts of the digestive tract or kidney. may also create adhesion points for secreted mucus

Cilia

microtubules project from cell membranes as hair that moves uniformly in one direction (wave like). They can move substances along the surface of a sheet of epithelial cells. (nicotine decreases ciliary action)